Method of producing an inturned bead metal cap in a rotary type die



C. C. GREEN DUCI June 7, 1966 3,254,619 AD METAL 3 Sheets-Sheet 2 METHOD OF PRO NG AN INTURNED BE 1 CAP IE 7 Filed Dec. 18, 1962 IN A ROTARY TYPE D [Illa June 7, 1966 c. c. GREEN METHOD OF PRODUCING AN INTURNED BEAD METAL CAP IN A ROTARY TYPE DIE 3 Sheets-Sheet 5 Filed Dec. 18, 1962 INVENTOR.

CLARENCE C- GREEN 3,254,619 METHOD OF PRODUCING AN INTURNED BEAD METAL CAP IN A ROTARY TYPE DIE Clarence C. Green, Manheim Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Filed Dec. 18,'1962, Ser. No. 245,472 4 Claims. (Cl. 113-121) This invention relates to a method of producing metal closures and more particularly to a method of producing threaded metal closures having'an inturned bead on the lower portion of the skirt.

In the production of metal closures a hat-shaped blank is formed on a punch press from suitable sheet metal stock. This blank may have either a flat top or a domed top, depending on the design of finished closure desired, but in either case there is projecting from the circular domed top or flat top a depending skirt section forminga cylinder with the top closing one end of the cylinder. The other end of the cylinder wall opposite the closed end is provided with an outwardly projecting flange which completely surrounds the cylinder and is disposed substantially at a right angle with respect thereto.

In the formation of the finished closure from this blank the top of the blank remains unaltered while the skirt or cylinder portion is formed to the desired shape and the projecting flange is rolled into a bead ot conceal the cut edge and improve the appearance of the lower extremity of the closure skirt.

It is an object of this invention to provide a method of producing metal screw closures having an inturnedbead on the lower extremity of the skirt.

It is another object of this invention to provide a method whereby metal closures having an inturned bead can be produced on conventional rotary threading equipment.

In forming the thread and decorations on metal closures it has been common practice to utilize rotary threading equipment. In this equipment the closure blank to be threaded is placed on a mandrel with the'interior of the top of the closure blank in engagement with the end of the mandrel. The cylindrical skirt surrounds the mandrel, and the flange projects from the mandrel at right angles thereto.

The mandrel moves through a predetermined circular orbit. The portion of the mandrel surrounded by the cylindrical skirt portion of the closure is made up of a set of forming tools commonly referred to as internal tools. Positioned along the path of the orbital travelof the mandrel and closure blank is a complementary set of forming tools commonly referred to as the external tools.

The arrangement of the internal tools and the external tools with respect to each other is such that the clearance between the two is approximaely thesame as the thickness of the metal in the blank with the exception of the knurling tools close to the top of the closure blank. These knurling tools are positioned from one another about one-half the thickness of the metal in the closure blank so that the metal is actually pinched between the .two sets of tools. With this arrangement rotation of United States Patent Q the closure blank about its central axis is assured while- 3,254,619 Patented June 7, 1966 In order that this invention may be more readily understood, it will be describedin connection with the "attached drawing in which:

FIGURE 1 shows the relative position of the internal and external tools at the start of the beading operation;

FIGURE 2v shows the relative position of the internal and external tools with the bead formed;

FIGURE 3 shows the relative position of the internal and external tools during the threading operation;

FIGURE 4 is a diagrammatic view showing the relative position of the tools which are external of the mandrel and also shows the section lines from which FIGURES 1, 2 and 3 are taken;

FIGURE 5 shows one of the closure blanks after it has been stamped from the metal and before it has bee-n placed on the mandrel of the rotary threading device; and

FIGURE 6 shows a finished closure having an inturned bead.

Referring to FIGURE 5 there is shown a metal clo sure blank 2 having a domed top 3, a skirt portion 4 and an outwardly projecting flange 5. While the metal blank of FIGURE 5 looks the same as the metal blank used in the production of closures having an outturned bead, there is a slight difference in the height of the blank. For example, in the blank for the outturned bead cap the skirt portion 4 is longer than the skirt portion of the blank for the inturned bead cap. FIGURE 1' shows this blank in position on a rotary threader between the internal and external threading tools. The internal tools are carriedon a mandrel 6 and are held thereon by means of a cap screw 7 which fits into the end of the mandrel. These internal tools are keyed to the mandrel so they will rotate therewith. The tools compris a knurling tool 8, a threading tool 9 and a bead support 10. The mandrel is rotated by means of a pinion 11 which meshes with a sun gear 12 on the stationary part of the equipment. The closure blank 2 is held on the mandrel 6 by means of a pressure pad 13 which in the specific embodiment here illustrated is concave in the area 14 to accommodat a domed closure blank. It is essential that the closure blank be properly positioned on the mandrel axially to ensure that the component parts of the closure formation tools FIGURE 1 for performing the inturned bead and those for performing the outturned bead is as follows: The blank 2 is made with the skirt portion 4 slightly shorter than the conventional blank. This positions the flange 5 in a different area of the eccentric prebead track 15 so that the edge of the flange 5 engages the cam surface 16 in an area where this cam surface forces the edge of the flange in a downward direction following the contour of the eccentric bead track 15. Due to the fact that the projecting flange 5 is totally unsupported in this embodiment, it is essential that the force applied to the edge of the flange 5 be applied in a constant uniform manner and in the right area of the prebead track 15. In forming the outturned bead, the deeper blank positions the projecting flange 5 along the surface 17 of the prebead track which supports the flange so it can turn in one direction only. With the formation of the inturned bead the bending of metal applies a force in the area 18 of the closure blank 2 where the projecting flange 5 joins the cylindrical skirt portion 4. This force is in a direction toward the interior of the closure blank 2 and tends to wrinkle or buckle the blank in the area 18. To prevent this-wrinkling or buckling of the skirt of the closure blank in the area 18 means must be provided to support the closure blank in the area 18. In order to get this added support the prebeading of the cap is performed at a point where the relationship between the internal thread tool 9 and the eccentric prebead track 15 is such that the bottom portion of the thread tool 9 in the portion 19 is in engagement with or in very close proximity to the portion 18 of the closure blank. This portion 19 of the thread tool 9 gives the support necessary as the inward curl is started on the edge of the flange 5. The combination of the prebead track 15 and the support 19 serves to compress the flange and roll the bead on it. If the portion of the blank 18 is not supported, the force applied by the prebead track will cause the skirt of the blank to bend and the bead will then curl in the other direction forming a defective closure.

Referring now to FIGURE 4, it will be seen that the eccentric prebead operation just explained occurs While the internal tool is moving through the orbit shown by the arrow D. The short arrows E on the inner circumference of FIGURE 4 show each revolution of the closure blank as it travels in its orbital path. The long arrow F in the very inner circumference of FIGURE 4 represents 5.6 revolutions of the closure blank. The arrow G on outer circumference represents 6 revolutions of the mandrel. This is possible because the closure is of a diam eter slightly greater than the diameter of the mandrel. While the blank is moving along the prebead track 15, the blank makes slightly more than one complete revolution, during which the flange 5 is curled inwardly for the start of head formation. During this prebead formation the mandrel moves the distance of the arrow D on FIG- URE 4.

After the prebead operation described above is completed, the mandrel carrying the closure blank 2 next moves to the segment of the stationary tools designated by the arrow H and then on to the finish bead tool 20 which is in the area shown by the arrow I in FIGURE 4. At this point the closure has been rotated past the prebead track 15, the eccentric bead tool and the bead tool 20, and has made 4 complete revolutions on the mandrel. Up to this stage none of the threading or knurling operation has been performed. The blank now has a completed inturned head at the bottom of the skirt 4 which reinforces the skirt and holds the circular shape of the blank so that the subsequent knurling and threading operation does not distort the circular shape of the cap as occurs when the threading is done before or simultaneously with the beading operation.

From this stage the closure blank next moves on to the forming segment designated K in FIGURE 4. The relative positions of the tools in this segment are shown in FIGURE 3. In this segment the finish bead tool 20 urges the bead 21 into firm engagement with the support '10 carried on the mandrel so that this support 10 irons out any wrinkles or other irregularities present on the inner surface of the bead caused by the metal bending operation. This arrangement also ensures a bead having an internal diameter greater than the exterior diameter of the top of the cap so the caps can nest but in so doing will not stick together.

Referring now to FIGURE 3, it will be seen that the external thread forming tool 22 in cooperation with internal thread tool 9 forms the thread in the skirt 4 of the closure blank above the newly formed head. The knurl or other decoration around the top of the cap blank is formed by the knurling tool 23 which meshes the metal of the cap against the internal knurling tool 8. This knurling tool 8 is referred to as a driver. The term driver is used because this is the arrangement by which the closure is rotated as it moves through the cycle. The clearance between the internal tool and the external tool is slightly less than the thickness of the metal in the blank so that the metal is rolled or worked in this area to prevent slippage of the closure. In order to ensure that the knurling is not marred in any way, the tools are arranged so that the knurling operation takes place only during the last revolution of the closure. This must be one complete revolution with no excess so as to prevent marring of the knurling which would occur if the knurls do not come in register during the second revolution.

It is essential in carrying out this operation that the arrangement be such that the internal tools rotate and the external tools remain stationary. If both sets of tools were to rotate, it would be diflicult to keep the various parts in register. The general arrangement of tools for carrying out this method is the same as for producing closures having an outturned head. The difference is in the design of the heading tools, the relation of the tools to one another as well as the type of blank being formed. The method here under consideration uses conventional rotary threading equipment with a different tool design and a different formation in the bead-forming track to ensure that the bead is curled inwardly and is properly ironed to prevent wrinkles.

One of the problems in forming inturned bead metal closures of this type results from the fact that in the formation of the beads the bottom of the skirt is pushed inwardly to an extent that when the caps are placed in a hopper the opening in the bottom of the cap is slightly less than the external diameter of the top of the cap. When this occurs the caps will nest and stick together so that they cannot be properly hoppered. By the method here under consideration the bead is positioned on the bottom of the skirt in such a manner that the clearance inside the bead diameter is greater than the top of the cap. This can be seen in FIGURE 3 where the bead flares out so that in those cases where the caps nest within one another in a hopper they can be easily separated and fed freely through the hopper.

It will be clear from the foregoing that I have developed a method whereby a conventional screw thread closure can be produced having an inturned bead on the lower extremity of its skirt rather than the conventional outturned head. This is an advantage not only from an appearance standpoint but also in the free movement of the caps in conventional capping equipment.

I claim:

1. A method of forming a threaded closure having a head in the area below the thread from a blank comprising a top, a depending skirt portion disposed substantially at right angles to said top and an outwardly projecting flange at the extremity of said skirt opposite the top, the steps comprising placing said preformed blank on rotatable forming tools on a mandrel so that the skirt portion of the blank is in engagement with said forming tools, moving said blank through a predetermined orbit in close proximity to complementary forming 'tools on the exterior of the skirt, engaging the cut edge of said flange with a forming track on the external tools to bend the flange while supporting the blank at the joint between the skirt and the flange by the forming tool carried by the mandrel, completing the formation of a bead from the outwardly projecting flange while urging the inner portion of said bead against the support carried by said mandrel to smooth out any wrinkles which form on the inner surface of the bead, and thereafter forming a screw thread on the skirt of the blank between the newly formed bead and the top of the skirt.

2. A method of forming a threaded closure with an inturned head in the area below the thread from a blank comprising a top, a depending skirt portion disposed substantially at right angles to said top and an outwardly projecting flange at the extremity of said skirt opposite the top, the steps comprising placing said preformed blank on rotatable forming tools on a mandrel so that the skirt portion of the blank is in engagement with said forming tools, moving said blank through a predetermined orbit in close proximity to complementary form ing tools on the exterior of the skirt, engaging the cut edge of said flange with a forming track on the external into engagement with an external eccentric bead form ing track while the inner portion of said head is supported by said mandrel, and thereafter urging the com pleted head into engagement with a finish beadtrack to smooth out any wrinkles which form on the inner surface of the bead.

3. A method similar to claim 2 in which screw threads are formed above the inturned head on the skirt of the blank.

4. A method in accordance with claim 3 in which a screw thread is formed after the formation of the inturned bead is completed.

References Cited by the Examiner UNITED STATES PATENTS 1,658,603 2/1928 Kowal 113--121 2,022,949 12/1935 Bell 15372 2,024,262 12/1935 Williams 153-2 2,045,602 6/1936 Huntsman 1537 2,147,804 2/1939 Williams et al 113121 2,308,276 1/ 1943 Gibbs 1532 CHARLES W. LANHAM, Primary Examiner.

R. D. GREFE, Assistant Examiner. 

1. IN A METHOD OF FORMING A THREADED CLOSURE HAVING A BEAD IN THE AREA BELOW THE THREAD FROM A BLANK COMPRISING A TOP, A DEPENDING SHIRT PORTION DISPOSED SUBSTANTIALLY AT RIGHT ANGLES TO SAID TOP AND AN OUTWARDLY PROJECTING FLANGE AT THE EXTREMITY OF SAID SHIRT OPPOSITE THE TOP, THE STEPS COMPRISING PLACING SAID PREFORMED BLANK ON ROTATABLE FORMING TOOLS ON A MANDREL SO THAT THE SKIRT PORTION OF THE BLANK IS IN ENGAGEMENT WITH SAID FORMING TOOLS, MOVING SAID BLANK THROUGH A PREDETRMINED ORBIT IN CLOSURE PROXIMITY TO CONPLEMENTARY FORMING TOOLS ON THE EXTERIOR OF THE SKIRT, ENGAGING THE CUT EDGE OF SAID FLANGE WITH A FORMING TRACK ON THE EXTERNAL TOOL TO BEND THE FLANGE WHILE SUPPORTING THE BLANK AT THE JOINT BETWEEN THE SHIRT AND THE FLANGE BY THE FORMING TOOL CARRIED BY THE MANDREL, COMPLETING THE FORMATION OF A BEAD FROM THE OUTWARDLY PROJECTING FLANGE WHILE 